Generation of user equipment identification specific scrambling code for the high speed shared control channel

ABSTRACT

A code is produce for use in scrambling or descrambling data associated with a high speed shared control channel (HS-SSCH) for a particular user equipment. A user identification of the particular user equipment comprises L bits. A ½ rate convolutional encoder processes at least the bits of the user identification by a ½ rate convolutional code to produce the code.

[0001] This application claims priority to U.S. Provisional ApplicationNo. 60/378,170, filed May 13, 2002 and to U.S. Provisional ApplicationNo. 60/378,509, filed May 7, 2002.

BACKGROUND

[0002] The present invention relates to wireless communication systems.More particularly, the present invention relates to user equipmentidentification specific scrambling sequences for high speed sharedcontrol channels (HS-SCCH).

[0003] A high speed downlink packet access (HSDPA) is proposed forwideband code division multiple access communication systems. HSDPAallows for high downlink data rates to support multimedia services.

[0004] To support HSDPA, high speed shared control channels (HS-SCCHs)are used. The HS-SCCHs are used to signal vital control information tothe user equipments (UEs). Each HS-SCCH has two parts, referred to asPart-1 and Part-2. Part-1 carries time critical information needed bythe UE. This information includes the channelization code set and themodulation type used by the high speed physical downlink shared controlchannel (HS-PDSCH) which carries the HSDPA payload. This information isvital to support HSDPA, since HSDPA uses adaptive modulation and coding(AMC).

[0005] To obtain its Part-1 information, each HSDPA UE monitors up tofour HS-SCCHs for its information. The information for a particular UEis distinguished from other UEs by its UE identification (UE ID)specific scrambling sequence. The UE processes each monitored HS-SCCHwith its UE ID specific scrambling sequence to detect the HS-SCCHintended for the UE. After processing, the UE determines on whichHS-SCCH, if any, information was carried using its scrambling sequence.The UE descrambles the data carried on Part-1 of its HS-SCCH using itsscrambling sequence.

[0006] Until recently, a 10 bit UE ID was used as the basis for the UEID specific scrambling sequence. In this case, this UE ID was convertedinto a 40 bit scrambling sequence. To turn the 10 bit UE ID into the 40bit UE ID specific scrambling sequence, the 10 bit UE ID is processed bya Reed-Muller block to produce a 32 bit code. The first 8 bits of theproduced code are repeated and appended onto the back of the 32 bit codeto produce a 40 bit code.

[0007] Although it is proposed to extend the UE ID length to 16 chips,the current proposal for the HS-SCCHs uses a 10 bit UE ID. This UE ID isconverted into a 40 bit scrambling sequence. To turn the 10 bit UE IDinto the 40 bit scrambling sequence, the 10 bit UE ID is processed by aReed-Muller block to produce a 32 bit code. The first 8 bits of theproduced code are repeated and appended onto the back of the 32 bit codeto produce a 40 bit code.

[0008] To reduce the occurrence of false detections, it is desirable tohave good separation between the produced scrambling codes for each UEID. Accordingly, it is desirable to have alternate approaches toproducing scrambling codes.

SUMMARY

[0009] A code is produced for use in scrambling or descrambling dataassociated with a high speed shared control channel (HS-SSCH) for aparticular user equipment. A user identification of the particular userequipment comprises L bits. A ½ rate convolutional encoder processes atleast the bits of the user identification by a ½ rate convolutional codeto produce the code.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1A is a preferred diagram of a circuit for producing a codeassociated with a particular user for a HS-SCCH.

[0011]FIG. 1B is a diagram of a rate matching block used in conjunctionwith FIG. 1A.

[0012]FIG. 2A is a preferred diagram of a circuit for producing a codeassociated with a user identification of 16 bits.

[0013]FIG. 2B is a diagram of a rate matching block used in conjunctionwith FIG. 2A.

[0014]FIG. 3 is a simplified user equipment using the UE ID specificscrambling code.

[0015]FIG. 4 is a simplified base station using the UE ID specificscrambling code.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Although the preferred embodiments are described in conjunctionwith the preferred application of the invention for use with the HSDPAof the third generation partnership project (3GPP) wideband codedivision multiple access (W-CDMA) communication system, the inventioncan be applied to other code division multiple access communicationsystems. FIGS. 1A and 1B are diagrams of a preferred UE ID specificscrambling sequence circuit. A UE ID, X_(UE), of length L is input intothe circuit. L can be any length, such as 8 bits, 10 bits, 16 bits, etc.The UE ID, X_(UE)={X_(UE1), . . . , X_(UEL)}, is input into a ½ rateconvolutional encoder 10 as shown in FIG. 1A. Along with the UE ID,extra bits, such as zeros, may be added to the end of the input stringto extend the length of the input string and, accordingly, the outputstring. The use of a ½ rate convolutional encoder 10 provides for a highlevel of code separation between the output strings produced bydifferent UE IDs. Additionally, current proposed 3GPP W-CDMAcommunication systems utilize a ½ rate convolutional encoder 10 for aforward error correction (FEC) technique. Accordingly, no additionalhardware is required to generate the convolutionally encoded UE IDspecific scrambling sequence. After encoding, based on the length of theoutput string, a rate matching stage 12 may be added to puncture bits toobtain a desired string length.

[0017]FIGS. 2A and 2B are diagrams of preferred UE ID specificscrambling sequence circuit for a preferred UE ID codes of length 16,L=16. The 16 bit UE ID, X_(UE)={X_(UE1), . . . , X_(UE16)}, is inputinto a ½ rate convolutional encoder 14 along with eight zero bitsappended onto the end of the input string. As a result, the input stringis X_(UE1), . . . , X_(UE16), 0, 0, 0, 0, 0, 0, 0, 0. After beingprocessed by the ½ rate convolutional encoder 14, the output code is 48bits in length, C_(UE)={C_(UE1), . . . , C_(UE48)}.

[0018] To reduce the length of the code to a preferred length of 40bits, eight bits are preferably punctured. FIG. 2B illustrates the ratematching stage 16 to perform the puncturing. After the rate matchingstage 16, the effective length of the scrambling code is 40 bits.

[0019]FIG. 4 is a simplified diagram of a user equipment descrambling aHS-SCCH using the UE ID specific scrambling code. The UE ID scramblingcode is mixed, such as by exclusive-or gate 18, with the receivedHS-SCCH for use in recovering the encoded HS-SCCH data.

[0020]FIG. 3 is a simplified diagram of a base station scramblingencoded data with the UE ID specific scrambling code for transfer overthe HS-SCCH. The encoded data is mixed with the UE ID scrambling code,such as by an exclusive-or gate 20, for a particular user. The scrambleddata is used to produce the HS-SCCH for transfer to the particular user.

What is claimed is:
 1. An apparatus comprising: an input configure toaccept a user identification comprising L bits; and a ½ rateconvolutional encoder for processing at least the bits of the useridentification by a ½ rate convolutional code to produce a code used forscrambling a high speed shared control channel (HS-SCCH).
 2. Theapparatus of claim 1 further comprising a rate matching block forpuncturing bits after the production of the ½ rate convolutional code.3. A user equipment comprising: an input configure to accept a 16 bituser identification; and a ½ rate convolutional encoder for processingthe 16 bit user identification code with eight appended zero bits toproduce a 48 bit code for use in descrambling a high speed sharedcontrol channel (HS-SCCH).
 4. The user equipment of claim 3 furthercomprising a rate matching block for puncturing eight bits after theproduction of the 48 bit code.
 5. A user equipment comprising: an inputconfigure to accept a 16 bit user identification; and means for ½ rateconvolutional encoding the 16 bit user identification code with eightappended zero bits to produce a 48 bit code for use in descrambling ahigh speed shared control channel (HS-SCCH).
 6. The user equipment ofclaim 5 further comprising means for puncturing eight bits after theproduction of the 48 bit code.
 7. A base station comprising: an inputconfigure to accept a 16 bit user identification; and a ½ rateconvolutional encoder for processing the 16 bit user identification codewith eight appended zero bits to produce a 48 bit code for use inscrambling a high speed shared control channel (HS-SCCH) for a userequipment associated with the 16 bit user identification.
 8. The basestation of claim 7 further comprising a rate matching block forpuncturing eight bits after the production of the 48 bit code.
 9. A basestation comprising: an input configure to accept a 16 bit useridentification; and means for ½ rate convolutional encoding the 16 bituser identification code with eight appended zero bits to produce a 48bit code for use in scrambling a high speed shared control channel(HS-SCCH) for a user equipment associated with the 16 bit useridentification.
 10. The base station of claim 9 further comprising meansfor puncturing eight bits after the production of the 48 bit code.